Angioplasty balloons are typically produced by a combination of extrusion and stretch blow molding. The extrusion process is used to produce the balloon tubing, which essentially serves as a pre-form. This tubing is subsequently transferred to a stretch blow-molding machine capable of axially elongating the extruded tubing. Certain known processes involve blow-molding a balloon, in which a polymeric extrudate can be stretched in both radial and axial directions.
The materials used in balloons for dilatation are primarily thermoplastics and thermoplastic elastomers such as polyesters and their block co-polymers, polyamides and their block co-polymers, and polyurethane block co-polymers. For example, certain balloon materials include polyester-ether copolymers and polyether-polyamide copolymers. Dual-layer balloons are also known that include an inner layer that includes a polymer selected from the group consisting of a polyester, polyether, polyamide, and copolymers thereof, and an outer layer that includes a polyamide.
The unique conditions under which balloon dilatation is performed typically require extremely thin-walled, high-strength balloons that, when deflated, are flexible and trackable enough to be maneuvered through small, tortuous vessels. Balloons made from high-strength polymers, while exhibiting high burst strengths, exhibit less flexibility and trackability than desired. The addition of plasticizer to the materials increases the softness and flexibility of the balloon; however, the use of plasticizer can limit the balloons applicability as a bio-compatible material. Balloons that exhibit high burst strengths that can be used in stent delivery, but also exhibit high flexibility and trackability, are desired. New balloon materials are therefore needed to tailor the properties of the balloon and produce high-strength and highly flexible balloons for medical applications.